Rather than get buried in all the details of Bush's service point accumulation and whether or not he technically fulfilled his military commitment to the National Guard, this whole issue centers around a few plain points that are on the record, and easily remembered.
http://the.honoluluadvertiser.com/article/2004/Feb/13/op/op02a.html#1.Bush has been candid about why he enlisted in the Guard. He told one reporter: "I was not prepared to shoot my eardrum out with a shotgun in order to get a deferment. Nor was I willing to go to Canada. So I chose to better myself by learning how to fly airplanes." (Critical point; volunteering for active service in Vietnam was never even considered.)
#2.(learning how to fly airplanes)...wasn't technically available to Bush. He didn't qualify for either a direct commission or flight training. But he received both when he jumped several waiting lists for a coveted spot in the Texas Air National Guard. (Reason this is a concern, in the words of Colin Powell "I am angry that so many of the sons of the powerful and well placed ... managed to wangle slots in Reserve and National Guard units," Secretary of State Colin Powell wrote in his memoirs. "Of the many tragedies of Vietnam, this raw class discrimination strikes me as the most damaging to the ideal that all Americans are created equal and owe equal allegiance to their country.")
#3.Bush was a fully trained pilot who had undergone a rigorous two-year flight-training program that cost the Pentagon nearly $1 million when, in April 1972, he climbed out of a military cockpit for the last time. He still had two more years to serve.
(Critical point; The taxpayers spent $1,000,000 so he could read magazines and training manuals while he pursued other interests in Alabama. Bush has a long history of wasting taxpayers money when it comes to military flights; his TANG training, his "Mission Accomplished" carrier photo-op, and his Daytona 500 AF1 "buzz the tower" campaign stunt are just a few examples.)